Effects of climate, socioeconomic development, and greening governance on enhanced greenness under urban densification

Urban vegetation is essential for the quality of life in cities. Despite direct vegetation loss during urban expansion, urbanization can indirectly enhance vegetation greening through various factors. Yet, it remains unclear what conditions promoted these greening trends within cities. We quantified the greenness trends in 294 Chinese cities based on satellite imagery (2001 - 2018), which we then explained with climate and socioeconomic indicators, particularly considering the National Garden Cities incentive program for urban greening (NGC). Results reveal large potential for enhancing greenness under urban densification, with larger cities leading urban greening development. We further show that the effectiveness of NGC in promoting enhanced urban greenness is context-dependent, particularly depending on aridity, which is not sufficiently considered in current policy. Our findings show that the indirect vegetation growth index is an effective tool to evaluate urban greening governance and highlight the importance of tailoring regional greening strategies to local conditions for sustainable urban vegetation development.